Snowbirds to be upset by snow and cold in early December

Wasn’t going to blather about clouds and weather for a few days since there wasn’t any, just sit around and wait for those end of November storms to get  here, then regale you with cloudy pictures.

But when I went to the NOAA spaghetti factory just now, I was blown away, beside myself, when I saw those outputs.  Being one of the meteorological sophisticates, I suspect you’ve already trampled these maps.  But, at the risk of being redundant again and again, here are a couple of jaw droppers from last night’s global data with errors input into the computer model at the beginning of the run to see how much the upper level forecasts change.  There are always errors in measurements, they’re not perfect, and so by deliberately putting errors in models, we can see that range of differences in the outcomes.  At first, there are virtually no differences because the errors are tiny.  But over time their effect grows.

In these plots below, when the two colors of crazy lines cluster (red, representing the warmer side of the jet stream,  and blue, the colder side) , it means the errors had little effect, and the forecast of a general pattern on the jet stream is one you can have great confidence in.

Below, a forecast via the “errorful ensembles” to be alliterative there for a second,  in which the confidence can be quite high showing that a gigantic cold trough will sit atop most of the western US in the coming 9-12 days.  Really, these are incredible:

Valid at 5 PM AST December 2nd. A massive pile of cold air is bound to be planted on top of the West with low temperatures and freezing levels by this time. Should make quite the news stories I would think when this comes around.
Valid at 5 PM AST December 2nd. A massive pile of cold air is bound to be planted on top of the West with low temperatures and freezing levels by this time. Should make quite the news stories I would think when this comes around.
Here’s 24 h later, at 5 PM AST, December 3rd. Look at how far the cluster of red lines is to our south, WAY down in southern Baja. Wow. The clusteriing of blue lines in the West and in Arizona suggests a very cold early December is in the bag for us. These maps also show that the SE part of the US will be nice and toasty in comparison.

So, how will it play out?

Well, we already have rather quickly passing cold troughs with their cold fronts ahead in late November,  one that passes late on the 27th  likely to boost our Sutherland Heights precip totals to our average value or above.

Then,  the cold pattern gets amplified by this gargantuan  trough that sets up a few days after those first couple of cold shots, setting the stage for cold and colder blasts.  So the beginning of our cold weather and snowbirds muttering that they came to Arizona too soon,  is just a few days ahead (followed by a “sucker hole” of brief temperature recovery and a few sunny days.   (Well, I might be complaining, too, since cloud maven person, the writer,  moved to Arizona from Seattle to be warm all day,  every day.  haha, sort of.)

On the other hand, there’ll be some great cloud shots in spite of the cold, and you and I, the rest of the cloud people,  will both manage, warmed by the euphoria of being alive with such gorgeous scenes and exciting, changeable weather.

BTW, will close this shot-from-the-hip blog with a forecast of snow in Catalinaland in early December.  That’s right, CMP is expecting measurable snow right here in Catalina.

Remember our slogan, “Right or wrong, you heard it here first!”

“Alive and local”,  CMP

The End




By Art Rangno

Retiree from a group specializing in airborne measurements of clouds and aerosols at the University of Washington (Cloud and Aerosol Research Group). The projects in which I participated were in many countries; from the Arctic to Brazil, from the Marshall Islands to South Africa.


  1. Hi Art: I’m still kind of skeptical here about that forecast. You see, I haven’t even seen ONE day with below freezing temperatures yet! But, if what you say is correct , we’re in for a long awaited “real” winter here.

    1. Hi, Roland,

      Nice to hear from you again.

      Well, of course, it wasn’t my forecast exactly, BUT an interpretation of the ensembles showing a big trough in the West. Now I did notice that for some model (WRF-GFS) runs, there was no HUGE trough, but a trough.
      But those can be considered noise (I hope) in a sense, actual runs with errors we don’t know about, and the REAL solution will converge to what the ensembles suggested, a major trough, not “just a trough.”

      Now I haven’t looked at the models lately, but a met friend just sent an e-mail that a gigantic cold wave was heading into the West in about 10 days. I still have not looked, kind of a superstitiion since I stuck my neck out so far in advance!

      It will be fun seeing what happens.

      Hope you are well,


      1. Thanks, Art. I know nothing is really “etched in stone’ at this point, and 10 days is pretty far away. Actually a friend lately has been asking me if it will snow at Christmas(that’s even farther away! I just wrote my first Christmas card last night). Right now, the snow has been falling- mostly above 2000 feet up in the mountains, so it’s getting closer!

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